24bf92169e471ac956f6ac350866e5a7 dv5029.pdf 59f673c918eb70cdfea08b1b93f5738572001b20 dv5029.pdf d13d6cc14d01404e8f713ae811c062cb7dc2abcc1c954bc9d33555755df63b32 dv5029.pdf Title: Common misconceptions in crystallography and crystal optics Creator: pdftk 3.0.0 - www.pdftk.com Producer: International Union of Crystallography CreationDate: Sun Feb 1 13:00:00 2026 CET ModDate: Sat Jan 31 20:03:38 2026 CET Custom Metadata: no Metadata Stream: yes Tagged: no UserProperties: no Suspects: no Form: none JavaScript: no Pages: 9 Encrypted: no Page size: 609.676 x 793.701 pts Page rot: 0 File size: 12432495 bytes Optimized: yes PDF version: 1.6 name type encoding emb sub uni object ID ------------------------------------ ----------------- ---------------- --- --- --- --------- Optima_Bold Type 1 Builtin yes no yes 296 0 Optima_Italic Type 1 Builtin yes no yes 297 0 Optima_Roman Type 1 Builtin yes no yes 298 0 Times-93Roman Type 1 Builtin yes no yes 299 0 Times-93Italic Type 1 Builtin yes no yes 300 0 TeX_Times_Math_Symbol Type 1 Builtin yes no yes 221 0 TeX_Times_Math_Italic Type 1 Builtin yes no yes 222 0 Times-93Bold Type 1 Builtin yes no yes 235 0 Jhove (Rel. 1.28.0, 2023-05-18) Date: 2026-02-19 04:13:16 CET RepresentationInformation: dv5029.pdf ReportingModule: PDF-hul, Rel. 1.12.4 (2023-03-16) LastModified: 2026-02-18 10:16:40 CET Size: 12432495 Format: PDF Version: 1.6 Status: Well-Formed and valid SignatureMatches: PDF-hul MIMEtype: application/pdf Profile: Linearized PDF PDFMetadata: Objects: 333 FreeObjects: 1 IncrementalUpdates: 1 DocumentCatalog: PageLayout: SinglePage PageMode: UseNone Outlines: Item: Title: Abstract Destination: 1 Item: Title: 1. Introduction Destination: 1 Item: Title: 2. Methods Destination: 1 Item: Title: 3. Results and discussion Destination: 1 Children: Item: Title: 3.1. Cell restrictions Destination: 1 Item: Title: 3.2. Trigonal (crystal system) versus rhombohedral (lattice system), and the role of hexagonal Destination: 1 Item: Title: 3.3. XRD, a spectroscopic technique? Destination: 1 Item: Title: 3.4. Alloy versus compound Destination: 1 Item: Title: 3.5. Parallel Nicols Destination: 1 Item: Title: 3.6. Hourglass twinning or zoning Destination: 1 Item: Title: 4. Conclusions Destination: 1 Item: Title: Acknowledgements Destination: 1 Item: Title: Conflict of interest Destination: 1 Item: Title: Data availability Destination: 1 Item: Title: References Destination: 1 Info: Title: Common misconceptions in crystallography and crystal optics Creator: pdftk 3.0.0 - www.pdftk.com Producer: International Union of Crystallography CreationDate: Sun Feb 01 13:00:00 CET 2026 ModDate: Sat Jan 31 20:03:38 CET 2026 ID: 0xed75ae1acf22c280cc9a4d285e3b6b9a, 0xee1816b7a40a7b6d2c6365ff8909db4e Filters: FilterPipeline: FlateDecode FilterPipeline: DCTDecode Images: Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1057 ImageHeight: 347 ColorSpace: CMYK BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1385 ImageHeight: 870 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 2141 ImageHeight: 293 BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/jpg CompressionScheme: JPEG ImageWidth: 211 ImageHeight: 208 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Image: NisoImageMetadata: FormatName: image/png ImageWidth: 2520 ImageHeight: 822 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1260 ImageHeight: 805 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 2520 ImageHeight: 831 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1385 ImageHeight: 1038 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1260 ImageHeight: 851 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1385 ImageHeight: 870 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1260 ImageHeight: 868 ColorSpace: RGB BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Image: NisoImageMetadata: FormatName: image/png ImageWidth: 1385 ImageHeight: 905 BitsPerSample: 8 BitsPerSampleUnit: integer Filter: FlateDecode Fonts: Type1: Font: BaseFont: Optima_Bold FirstChar: 33 LastChar: 251 FontDescriptor: FontName: Optima_Bold Flags: Symbolic, ForceBold FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true Font: BaseFont: Optima_Italic FirstChar: 33 LastChar: 251 FontDescriptor: FontName: Optima_Italic Flags: Symbolic FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true Font: BaseFont: Optima_Roman FirstChar: 33 LastChar: 251 FontDescriptor: FontName: Optima_Roman Flags: Symbolic FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true Font: BaseFont: Times-93Roman FirstChar: 32 LastChar: 251 FontDescriptor: FontName: Times-93Roman Flags: Symbolic FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true Font: BaseFont: Times-93Bold FirstChar: 32 LastChar: 251 FontDescriptor: FontName: Times-93Bold Flags: Symbolic, ForceBold FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true Font: BaseFont: Times-93Italic FirstChar: 32 LastChar: 251 FontDescriptor: FontName: Times-93Italic Flags: Symbolic FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true Font: BaseFont: TeX_Times_Math_Symbol FirstChar: 1 LastChar: 138 FontDescriptor: FontName: TeX_Times_Math_Symbol Flags: Symbolic FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true Font: BaseFont: TeX_Times_Math_Italic FirstChar: 1 LastChar: 127 FontDescriptor: FontName: TeX_Times_Math_Italic Flags: Symbolic FontBBox: -50, -180, 1000, 720 FontFile: true ToUnicode: true XMP: True This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 UK: England & Wales License</a>. This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 UK: England & Wales License</a>. 2026-02-01 true 10.1107/S1600576725010635 10.1107/S1600576725010635 noindex 2026-02-01 true iucr.org iucr.org 10.1107/S1600576725010635 VoR doi:10.1107/S1600576725010635 J. Appl. Cryst (2026). 59, 239-247 [doi:10.1107/S1600576725010635] teaching and education application/pdf Common misconceptions in crystallography and crystal optics en Did you know that an X-ray diffraction pattern is not a spectrum? However, one in five scientific papers showing X-ray diffraction patterns refers to them as `X-ray spectra'. Further, and in contrast to what is stated in many reference books, a triclinic substance could have a cubic-shaped cell. In crystal optics the terminology `parallel Nicols' is almost always misused, and in the frame of polarizing microscope observations zoning is sometimes mistaken for twinning. In this paper, six recurring misconceptions in crystallography, including several related to mineral and crystal optics, are analyzed. Their prevalence is assessed through statistical data on their persistent appearances in peer-reviewed scientific literature. The objective of this study is to promote the correction of these misconceptions in academic communication and teaching. Furthermore, and according to some learning theories, the explanation of well established misconceptions could be used by teachers as an educational resource, offering powerful learning opportunities and contributing to talent development. 2026-02-01 International Union of Crystallography MISCONCEPTIONS X-RAY DIFFRACTION CELL RESTRICTIONS CRYSTAL OPTICS XRD SPECTRA Casas, L. 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